Criminologist Christopher Berry-Dee takes readers deep inside the dark minds of some of the most pitiless and dangerous people alive. Having spent years interviewing imprisoned criminals, including notorious serial killers, he discovered that the lack of remorse they showed was in many ways more terrifying than the crimes they had committed. Yet in the course of these conversations, the author also had the chance to interview his subjects' psychiatrists and, in doing so, uncovered a terrible truth: a monster can be hidden behind a friendly face. Some of these experts, he found, proved to have more in common with their patients than he would ever have expected. This book examines horrific crimes committed by some of the most remorseless and merciless people ever to have lived.